Air Con - W124 Estate - PLEASE READ

[toby120]

Hi All,
Newbie Toby here and I have problem... I know there is a lot about Air Con but I just cannot find anything to help... Here goes..

My beloved 1994 E280 Estate has now been at the local mercedes garage for the best part of 4 weeks due to the air con working for only 1 hour max and the slowly shutting down to nothing.. it is dealer fitted although the garage are not sure what brand.. it was fitted when the car was 4 years old at a cost of £1500 by Mercedes Official Dealership but the invoice only states the price..

The garage not seem to be at a dead end.. the fuses have all been replace and the clutch as well and still they cannot work it out.

It was blowing very cold and within the hour of working steam and ice bits came out of the front vents.
The problem seem to be the air con compressor won't switch off its on all the time...
The fans have also been checked and are working

PLEASE does anyone have any thoughts on this..

Kind Regards

Toby

 

[carat 3.6]

It's not very clear what problem your having, you mean it start's icy cold but then warms up?

 

[toby120]

Hi,
thanks for the reply sorry if I wasn't clear I'm not that good when it comes to the technical side of things..
So the problem is the air con in the car works vey well for 1 hour max icy cold but then on the dot of an hour it begins to shut down within 1hour 20min it has shut down completely..the vents are not pushing any thing out at all.
the garage have checked the fans and replace the fuses which i understand might have caused an issue. this hasn't fixed it.
they tell me that the the compressor is running all the time and won't switch off this is causing the air to shut down they have changed and tested the clutch and that is working fine. They and I are now at a lose end on what it can be..

does any one have a clue why the compressor is running all the time?
thanks again for the reply
Toby

 

[WG M-B]

Try the a/c relay

 

[roadhog]

There should be a couple of pressure switches in the system, the high pressure one should be telling the compressor (via the relay) to stop by disengaging the clutch.
The switches are located on the dryer/receiver (the small black cylindrical unit behind the nearside headlight). Easy to test, cheap enough to replace but you will need someone to empty the refrigerant form the system first.

It might be worth changing the dryer while you're in there, they have a limited lifespan. MB want around £100 for a new one, can be had for a lot less aftermarket though.

If it's a dealer fit air con it's likely a Diavia, factory fit was Behr.

 

[Mercland]

Few things to consider:
- What gas is the car on. If originally R12 then are they using correct amount of R134a gas as you only fill 80% amount of R134 to R12
- If the compressor is actually running all the time, I would suspect pressure switches first. These are not expensive. They are red capped with two wires coming out.
- You may still have a leak and gas may be leaking out within the hour. When was condensor last changed?

I have had to replace many parts of the A/C on my W124's including condensor, drier, compressor and some very expensive pipework. The car is getting older now. Seals dry up, pipes wear through, joints leak etc...

 

[RichardF]

If it's dealer fit, likely to be Diavia.

 

[jaymanek]

The diavia parts are a bit of mix and match.. We had to take an old condensor out and match it up at our supplier last time we did one.

 

[toby120]

Thank you everyone for all your reply's! I have forwarded them all to the garage so hopefully they will be able to fix the problem without breaking the bank! - although I have a feeling...the bank has been broken..if anyone else has any more ideas then please do let me know so I can see if we can fix this problem for myself and any other W124 owners!
THANKYOU again,
Toby